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` Dec. i3, 1927.

552,565 E. D. DUNNING PUMP Filed Feb. 26, 1924 3 She ets-Sheet l ATTY Dec, 13, 1927.

1,652,55 E. D. DUNNING PUMP Filed reuze, 1924 s sheets-Skeet 2 ,9 ZZ 5' jig! f4 ,e5 d l l 11 um INVENTOR ec. S, 1927. 1,652,565

E. D. DUNNING PUMP Filed Feb.2e, 1924 5 sheets-sheet 5 INVENTOR ,ZT/mfr. zmfz my' Y ATTORN l cationof said surfaces.

providing a relatively massive crank shaft Patented Dec. 13, 1927.

-. UNITED STATES PATENT PUMP.

Application flied February 26, 1924. Serial 110.695,14?.

other is compressing gas for refrigerators.

Various features of the invention may be embodied in pumps having'a single piston head, but they are shown herein as employed in connection with a double pump comprising two piston heads rigidly connected by a web and reciprocated in oppositely aligned cylinders by a special form' of ,scotch yoke driv-l ing means consisting of an eccentrictted between the 'adjacent bases of the piston heads and acting alternately on one and then on 'the other to force the compression strokesVv of each, the suction lstrokes being accomplished by traction through the web connection between the piston heads.

One object of the invention is to provide a rugged, practically unbreakable construction in which the operating parts have extremely large bearing surfaces, and lanother (.bj'ect is to provide for automatic force feed lubri- Another feature is and arranging it so that it may be mounted between bearings at both ends of the shaft. and which can 'be removed and replaced in 30 operative position within the device through an opening which is but little larger than y the-diameter of the eccentric. i Theabove and other features of my invention may be more readily understood from the following description in connection with the accompanying drawings, in which Fig. 1 is a Side elevation, partly broken away to longitudinal vertical section;

Fig. 2 is a vertical transverse section substantially along the broken line 2, 2, Fig. 1, but showing the shaft and eccentric in side Y elevation;

Fig. 3 is a plan view showing the stationary parts in horizontal section and the moving parts in plan;

' Fig. 4 is a detail side elevation of the drive shaft and eccentric;

Figs. 5 and 6 are respectively side and end elevations of the bronze slide bearings for the eccentric;

Fig. 7 is a side elevation of the double headed piston and web;

Fig. 8 is a section on the line 8, 8, Fig. 7;

Fig. 9 is a detail vertical section of the lubricating pump plunger;

Fig. 10 is a longitudinal section of a modied forni of pum with the piston and eccentric shown in e evation;

Fig. 11 is a detail showing one of the main bearings in horizontal section, with the drive shaft eccentric bearing and double headed piston in operating relation.

The embodiment shown in Figs. 1-9 inclusive is connected up as a two-cylinder compression pump, but it will be obvious that by other connections it ma be made a twocylinder vacuum pump, or 1t may both vacuumize and compress; or, if desired, it may be connected up as a two-stage compressor or vacuumizer, or both. In any of these cases, the more important elements and their operation will be as follows:

Piston heads 1, 2 having piston rings 3,

3, 4,'4, are connected base to base by web 5, 5, provided with strengthening ribs 6, 6. These piston heads reciprocate in opposite axially aligned cylinders 7, 8, having heat radiating ribs 9, 9. `These cylinders are preferably cast integral with the base 10, which is formed as an oil reservoir of ample ca acity.

he drivin'g means for the piston includes shaft 11, which is preferably integral with eccentric 12, which is provided with a collar 13. Theintegral extension 11?` is somewhat smaller than shaft 11, for a purpose to be described.

Encircling the eccentric 12 is a bronze collar 14, formed with bearing surfaces 15, l5, accurately fitting against and sliding upon surfaces 16, 16 of the piston heads.

The main bearing 20 for shaft 11 is in a removable closure block having a very wide bearing surface ink the lateral opemng 22 midway between the cylinders. The size of this opening is slightly greater than the diameter of the eccentric 12, and is in fact just the right size to be a loose fit for the collar 13.

The shaft extension 11a is journalled in a bushing 24 screwing into the opposite side of the cylinder casting, in alignment with the main bearing 20.

The above parts are assembled by inserting the double headed piston through an open end of one of the pump cylinders. The bronze bearing collar 14 is then fitted on the eccentric 12 snugly against collar 13. The shaft eccentric and collar are inserted through opening 22, with slidesurfaces 15, 15, in contact with the wear surfaces 16, 16 of the piston. The bushing 24 for the shaft extension 11a and the main bearing block Q1. for shaft 11 are moved axially into their operative positions, bearing 24 being held by its screw thread and Q1 being held b v suitable bolts 25, 25. The inner end of the bearing 20 maintains the eccentric collar 13 snugly engaging the bronze 14, forcing the latter against the vertical face of web pieces 5, 5 of the piston.

Preferably the bearing 24 extends through the slot between webs 5, into end engagement with eccentric 12. In such case. the slot has to be 'wider than the diameter of the bearing, and in such case the bronze collar 14 may be provided with vertical extensions 14, 14?, thus making it possible to have a desired latitude for vertical movement of the slide without danger of the upper or lower edges of the collar catchingv l in said Vslot of the piston.'

It will be obvious that the slide surfaces l5 and the internal surface 14 bearing upon the large diameter eccentric 12, are -well adapted to distribute all of the' loperating pressures over a relatively great surface and require minimum lu rication. `How ever, I find that the practical operating conditions and wear and tear of compressors of this kindv makes it desirable to have most copious lubrication. For this purpose drill lengthwise of 30,'having at least three branches, branch 31 leading to the bearing surface of the shaft within the bearing 24, the branch 32 leading to the wear surface of the eccentric, and the branch 33 leading to the wear surface of the main bearing. The duct 30 being drilled in from the end `of the shaft, is kept copiously supplied with oil by a reservoir 40 in bathing relation thereto. reservoir is shown as a cavity in the casting closed by plate 41 secured by screws 4Q.

While it is possible to makethiscavity large enough and deep enough for more or less effective gravity feed of the oil, I prefer to employ a force pump for keeping the reservoir full and also for maintaining a predetermined pressure of the `oil causing a forced feed through duct 30 and its branches. Such a pump is represented by pumpv piston 50, reciprocating in cylinder barrel 51, communicating aty the' bottom through opening 52 with thc base reservoir 10, and having itsI top portion extending into reservoir 40, in operative relation to any suitable eccentric surface carried by the drive shaft 11, or '11. In the specific form shown, this eccentric surface is in the form of a pin 53 axially into the end of shaft l1. This plug is formed with anoil duct communicating with the duct 30 in the shaft. Piston 5() has an internal passage 57, the bottom thereof being enlarged and fitted vwith :i check valve 58, forced downwardly by a bearing ring the shaft a main oil duct This on a screw plug 54. screwing.

beneath t-he piston being very slow by'rcason of its inertia and viscosity. each depression of the pump plunger causes'oil to flow in past. check lvalve 58 and out through 60 into the reservoir 40. At the end of the down stroke valve 58 closes automatically land under normal conditions the spring 61 returns the piston to the upper position, ready for another depression stroke. It will be noted, however, that when the reservoir 40 becomes full and sufficient back pressure accumulates, the spring 61 will not be able to force a full 11p-stroke of the piston. Consequently, as the pressure increases the lstrokes will become shorter and shorter, the pump being thus automatically self regulating to maintain a forced feed the pressure of which is dependent on the strength of spring 6l, the viscosity of the oil and the piston areas.

The ends of the pump cylinders are closed in by heads 70. 71, screwed to integral cylinder ianges 72, 72 by bolts 73, 73. In the present case the cylinder heads are shown as covering also the outlet ducts`75, 75 leading to the discharge outlet 76. The air passages and the valves are in these heads.k In each case there is an inlet leading to a valve cavity 81 covered by plate 82. The check valve comprises the stem 83, disk head 84, thrust washer 85, held by pin 86, whereby the thrust of spring 87 is applied to maintain the inlet valve S4 normally closed. The outlet valve 90 is slidably mounted in valve plug 91 and normally closed by spring 92.y

' Ihe valve chamber 93 communicates through passage 94 with the outlet 75 above referred to.

vIn Fig. 10, the moving parts are all substantially the same except that the` valves and connections are those of a two-stage pump. In this case the large low Apressure piston 1a operates to force partially compressed air or gas through pipe 7 valve 84a. of a smaller high compression piston Qa, whence the discharge of the doubly compressed air or gas is through outlet- 100.

I claim:

1. A double pump, including a straight bore casting forming opposed cylinders with an integral case between them; a web connected domste-headed piston having opposed slide surfaces transversely mounted in rigid relation on the rear faces of the heads and a longitudinally slotted guide surface on the rigid connecting portion at right angles to 5a to inlet` outlet 60 'discharglOl) said transverse Slide surfaces; a cooperating drive shaft` eccentric and bearing collar with the side face of the eccentric adjacent said longitudinal guide surface: and long bearing supports for the shaft on opposite sides of the eccentric, one bearing extending through the slot of the guide surface of the piston and both extending approximately to the eccentric.

2. A double pump. including a straight bore casting forming opposed cylinders with an integral case between them; a web connected double-headed piston having opposed slide surfaces transversely mounted in rigid relation on the rear faces of the heads and a longitudinally slotted guide surface on the rigid connecting portion at right angles to said transverse slide surfaces: a cooperating drive shaft. eccentric and bearing collar with the side face of the eccentric against. said longitudinal guide surface; and long hearing supports for the shaft on opposite sides of the eccentric, one bearing being carried by an endivise removable closure fitted within a lateral opening in the pump casing which opening is but slightly larger than the eccentric, and the other bearing being carried by an endwise removable member screwthreaded Within an opening in the opposite side of the pump casing. which opening is of sufficient diameter to permit angular shifting of the shaft and withdrawal of the eccentric through the opposite opening when said closures are removed.

3. A pump comprising cylinder. piston and a scotch yoke drive therefor. including a drive shaft supported in two outside bearings and carrying between the bearings an eccentric, the parts being formed with an oil duct drilled straight through from one end of the shaft and having branches for discharging oil through the shaft to both its hearings and to the periphery of the eccentric. said latter branch opening through a portion of the eccentric remote from the maximum pressure dead center thereof.

4. A pump comprising cylinder, piston and a scotch yoke drive therefor. including a drive shaft supported in two outside bearings and carrying between the bearings an eccentric. t-he parts being formed with an oil duct drilled straight through from one end of the shaft and having branches for di charging oil through thev shaft to both its bearings and to the periphery ot' the eccentric, said latter branch openingr ti; onfjh a portion of the eccentric remote from dead center points thereof.

5. A pump comprising cii'llnde-ii. crank case, piston and a scotch yokey drive therefor, including a drive shaft supported in two outside bearings and cari-ving between the bearings an eccentric. thc pari.-y l y formed with an oil duct from one cud of the shaft and having branches for discharging icing -main bearings connected with the entrance of oil through the shaft to both its bearings and to the periphery of the eccentric. in combination with an oil chamber in the bearings o'f onel of said shafts and in bathint relation to the entrance end of said oil duct. a pump having its intake in communication with the drainage .space in the crank case and its outlet in said oil chamber. the piston of the pump extending adjaccni thc drive shaft and an eccentric element on thi.` latter for direct drive of the pis-ion.

In a double pump. two. opposed cylinders and a connecting crank case in which oil drains by gravity: a Aweb-connected. double-headed piston; a scotch voke drive therefor. including an eccentric and integral drive shaft having an oil duct leading to a portion of the pcriphcr \1 of the eccentric, which is remote from dead center points thereof; an oil chamber connected with the 9' entrance end of said duct: a pump having its intake in communication with the drain- :ige space and its outlet in said oil chamber and means on the drive shaft for operating the pump. 90

7. ln a double pump. two opposed ctvlinders and a connecting crank ease in which oil drains by gravity: a web-connecterl. double-headed piston; a scotch Avokc drive therefor including an eccentric and integral drive shaft forn'ied with oil ducts leading lo the periphery of the eccentric and to thc main bearings; an oil chamber in one of said said duct: a pump having itsA intake in communication with the drainage space in the crank case and its oiulct in said oil chamber and means on the drive shaft for operating the pump.

8. A pump comprising a cylinder. .ci-ant; case and piston. and. in combination iiicrcwith, a .scotch yoke drive. clement. including yoke slide surfaces trani-'ift V nrcan:- ed in rigid relation on thc rea r tn the pif-.w I and a iongitndinal guide surface at right iii angles to said .slide surfaces and a cooper; ing drive shaft and eccentric. the side face of the, eccentric fitting agz'tiir-t said lengt tudinal guide surface to prevent axial rota.- tion of thc piston; a nf'fsviotaf ,--zwii collar fitting on the periA tricy and having slide transverse Slide surface means for holding .-,fiid collar zu cluding an annular i'lange on il f a thrust bearing to hold the f.- t centric in contact with the guide surface on the piston. collar clanrped between the hui flange on the eccci'itric.

t). A pump comprising or and an intermediate crank t connected. tlonblr \lieadcd p;

life

combination therewith. scotch rohe dri ments, including plan; sncf.. inrfznzes tudinal slide surface at versel'y mounted finv rigid relatonon the rear of the respective piston V tation of t-he piston and a non-rotatingbeartransversely to the axis said web being formed with 'a4 longitudinal vweb andan eccentric on ing collar fitting: onv the periphery of the eccentric and having slide surfaces engaging the transverse slide surfaces 4of the heads; and means vfor .holding said .collar in position, including an annular flange on thel eccentric, a thrust bearing to hold the face of the eccentric in Contact with the longitudinal guide surface-on the weband with the slide collar clamped between the latter. and said flange on-the eccentric. 'Y

Vl0. A' pump c'omprisingopposed cylinders and'fan intermediate crank case, a web-conneeted,l double-headed piston, the rear faces of the `piston heads being formed withoppiosit'e, plane bearing surfaces extending of the piston, and

guide surface vwith alongitudinal slot therethrough, inl combination with ascotch yoke drive therefor, including 'a drive shaft extending through said longitudinal slot in. the

' the drive shaft having' a side facev fitting-against saidrlongitudinal guide surface of the vweb. to .prevent axial rotation lof the ing bearing collar fitting piston; andv a non-rotaton the periphery of the eccentric and formed with plane slide surfaces engaging the transverse slide surfaces of the head and having a lateral slide surface engaging the longitudinal slide sur- .ace of the web.

1l. A pumpy comprising opposedcylinders and an' intermedlae crank case, a .web-connected, double-headed piston, the rearfaces of the pistonheads being formed with oppos-ite.y plane bearing surfaces extending trans versely to the axis .of the piston, and said web being formed .with a longitudinal guide surfacewi-th a longitudinal slot, in combination with a scotch yokefdrive therefr, fincluding a drive shaft extending through said longitudinal slot in the web onthe against said longitudinal 'guide' surface" of the .web to prevent axial rotation of the piston; and a non-rotating bearing collar fittingen` the .periphery of the eccentric and :formed with plane slide surfacesjengaging .the transverse slide surfaces .of the head and having a lateral slide surfaceengaging the longitudinal slide surface of the web; said collar being also formed with radial exten-l sion ymember-s aiording extensionslide surfaces at right angles to the slot through the web, adapted to bridge the slot when said collar is in the extreme upper orlower position.

12. In a'pump, inder, a piston, adriveshaftcasinga drive shaft in said casing, an eccentric on said drive shaft, vguiding extensions on said piston and extending across the drive,l Shaft. ad-

jacent one side of theeccenti'ic, and bearings for said shaft extending from the outside of the casing approximately to theV eccentric and having opposed end thrust bearing surfaces for xingthe plane of rotation of the eccentric, one of said bearings being in an endwise removable screw bushing and rextending between the guiding extensions.

Signed at New York, in the county of New York, and State of New York, this 25th day of February, A. D. 1924.

, ELMER D. DUNNING.

and aneccentric drive shafthaving a side face fitting `the vcombination of a "cyl-I' 

